This invention relates to an expansible sleeve type fluid flow control valve or pressure regulator of the type disclosed in U.S. Pat. No. 3,306,569, granted Feb. 28, 1967, to A. U. Bryant and assigned to the assignee of this invention.
Generally, the valve disclosed in that patent comprises a tubular housing having inlet and outlet flow passageways around which are sealed the ends of an elastomer expansible tube. The expansible tube is carried on a cylindrical core sleeve or cage that has a circular barrier across it intermediate its ends around which the expansible sleeve is sealed. There are inlet slots around the sleeve on the upstream side of the barrier and outlet slots on the downstream side of the barrier. A control pressure fluid is in a jacket around the sleeve so that flow through the valve is possible only when upstream fluid pressure acting on the expansible sleeve through the inlet slots is able to overcome the tension of the expansible sleeve plus the pressure fluid in the chamber around it to expand the sleeve outward. When this occurs, the fluid flows out the inlet slots and around the barrier, and then back through the downstream slots to the outlet flow passage.
Valves of this type have been highly successful in operation for various services, including the regulation of pressure. However, the elastomeric expansible tube, as a dynamic element, is subject to wear and occasional rupture and, therefore, periodic inspection and servicing is required. In order to inspect and service the expansible tube and other interior parts, it is generally necessary to remove the valve from the line in order to gain access to the core sleeve and expansible tube.